Antifungal strains M1-8 and M6-4 as biocontrol agents against Aspergillus flavus on peanut kernels

Aspergillus flavus is the main pathogenic fungi for peanut kernels, and it has highly negative economic and health impacts. To explore the biological control agent against A. flavus, two antagonistic strains were screened from 70 bacteria isolates from moldy stuff and identified as Burkholderia plantarii M1-8 and Burkholderia glumae M6-4. In vitro pathogen inhibition determination indicated culture filtrates of M1-8 and M6-4 had distinct inhibition zones and could decrease the mycelial growth of A. flavus. Furthermore, the biocontrol assay showed moldy rates of peanut seeds treated with culture filtrate were much lower than that of the control group. The biocontrol efficacy of M1-8 and M6-4 culture filtrate reached 88.6% and 84.2%, respectively, which were higher than that of the sorbic acid treatment group. Moreover, culture filtrate of M1-8 was tolerant to proteinase K, high light, pH and temperature (below 70°C), and had good stability of antifungal activity. The results indicate that these two antifungal strains could be used as biocontrol agents for controlling A. flavus during the peanut supply and storage period.